Bottle stopper



FIG. 1 is a front perspective view of a bottle stopper, showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a side view thereof; and,

FIG. 6 is a bottom view thereof.

The broken lines shown in the figures are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a bottle stopper, as shown and described. 